1. Field of the Invention
The present invention is generally directed to devices that measure the internal temperature of various products and to methods for using these devices. More particularly, the invention is directed to temperature probes for determining the internal temperature of a mass of tobacco product.
2. Discussion of Related Art
Tobacco leaves or leaf parts and other plant products are often stored as densely packed masses. Chemical reactions occur in moist plant matter which generate heat. Leaves and leaf parts typically have insulating properties which tend to prevent heat from escaping from the leaf mass to the ambient atmosphere. Consequently, when a tobacco leaf product (e.g., whole leaves or leaf parts such as the leaf lamina strips) are stored in a densely packed mass, the internal temperature of the leaf mass may rise. If the internal temperature of the tobacco leaf mass becomes too high, the tobacco leaf product may be damaged. At high temperatures, tobacco may change color, for example, or may carbonate, destroying the commercial value of the tobacco.
Several factors may need to be considered to successfully store packed tobacco, including sugar content, moisture content, and the temperature of the packed tobacco product. In some instances, the internal temperature of a tobacco leaf product mass may become high enough to cause spontaneous combustion, which can result in unwanted carbonization of the stored product that turns the product black and renders the tobacco commercially unusable.
Tobacco leaf product is generally enclosed within a container for storage, especially when received from a farmer or warehouse in loose form for packaging and transport to a manufacturer. Typical containers include a hogshead, which is a large cylindrical wooden container that holds approximately 900 pounds of product, and a PM80, which is a large, durable cardboard container capable of holding approximately 700–800 pounds of product. After a container is packed, the temperature is measured at or in the vicinity of the center mass of the tobacco to determine the “pack temperature” and then the container is covered. Thus, to prevent heat damage to tobacco, it is important to be able to determine the internal temperature of packed leaves.
Generally, if the internal temperature of a mass of tobacco product is below a threshold temperature at the time the tobacco product is enclosed within a container, the tobacco product can be stored without incurring heat damage, even when the storage is for a lengthy period. If the internal temperature is above a certain temperature, the container must be pulled from the line and reprocessed.
Known methods of measuring temperature have included removing a sample of tobacco from the interior of the leaf mass and measuring the temperature of the sample, which does not accurately predict the actual temperature within the package. Other methods use manual probes in the form of dial thermometers that are inserted into the bale and allowed to equilibrate over a period of eight to twelve hours before measuring the temperature. Both of these methods are performed when the bale is off line. Traditional methods and apparatuses for determining the internal temperature of a mass of tobacco leaf product have been time consuming, inaccurate, inefficient and/or costly.